python: expose Py_SetPythonHome and Py_GetPythonHome

 Fixes #71.

init.go

@@ -2,6 +2,7 @@ package python
 
 // #include "go-python.h"
 // char *gopy_ProgName = NULL;
+// char *gopy_PythonHome = NULL;
 import "C"
 
 import (
@@ -18,6 +19,7 @@ import (
 // will not change for the duration of the program’s execution.
 // No code in the Python interpreter will change the contents of this storage.
 func Py_SetProgramName(name string) {
+	C.free(unsafe.Pointer(C.gopy_ProgName))
 	C.gopy_ProgName = C.CString(name)
 	C.Py_SetProgramName(C.gopy_ProgName)
 }
@@ -41,3 +43,18 @@ func PySys_SetArgv(argv []string) {
 	}
 	C.PySys_SetArgv(argc, &cargs[0])
 }
+
+// Set the default “home” directory, that is, the location of the standard Python libraries. See PYTHONHOME for the meaning of the argument string.
+//
+// The argument should point to a zero-terminated character string in static storage whose contents will not change for the duration of the program’s execution. No code in the Python interpreter will change the contents of this storage.
+func Py_SetPythonHome(home string) {
+	C.free(unsafe.Pointer(C.gopy_PythonHome))
+	C.gopy_PythonHome = C.CString(home)
+	C.Py_SetPythonHome(C.gopy_PythonHome)
+}
+
+// Return the default “home”, that is, the value set by a previous call to Py_SetPythonHome(), or the value of the PYTHONHOME environment variable if it is set.
+func Py_GetPythonHome() string {
+	home := C.Py_GetPythonHome()
+	return C.GoString(home)
+}

init_test.go

@@ -14,3 +14,12 @@ func TestProgramName(t *testing.T) {
 		t.Fatalf("got=%q. want=%q", name, want)
 	}
 }
+
+func TestPythonHome(t *testing.T) {
+	const want = "/usr/lib/go-python"
+	python.Py_SetPythonHome(want)
+	got := python.Py_GetPythonHome()
+	if got != want {
+		t.Fatalf("got=%q. want=%q", got, want)
+	}
+}